Cristina Sevin packs lunches for her two teenagers in Annapolis, Md., on Nov. 22.

Maggie Starbard/NPR

Cristina Sevin knows the drill. Her 15-year-old son Isaac's first alarm goes off at 6:05 a.m.

When he sleeps right through it, Mom starts the nudging. But she also has to wake up 16-year-old Lily. She flips on the bedroom lights. "Lily, you gotta get up!"

They have to be out the door before 6:35 a.m. in their Annapolis, Md., neighborhood in order to catch the bus for a 7:17 school start. "I wish I didn't have to be awake right now," says Lily.

She barely has time to brush her teeth and grab a go-mug of hot tea before she and Isaac head out into the predawn darkness.

Cristina Sevin is convinced there's a better way to raise teenagers: Push back the start of school one hour. Instead of a 7:17 morning bell, how about 8:18?

Sevin's family is part of a growing grass-roots campaign advocating for later high school start times. A national petition to promote legislation that would prevent public schools from starting before 8 a.m., started by the group Start School Later, has thousands of signatures from all 50 states.

There have been years of debate on this issue. Sleep scientists argue that early high school start times conflict with teens' shifting circadian rhythms. Beginning in puberty, "adolescents are programmed to fall asleep later," says Dr. Judith Owens, who directs the Sleep Medicine Clinic at Children's National Medical Center in Washington, D.C. And she says many teenagers can't fall asleep before 11 p.m.

Because teenagers need eight to nine hours of sleep, waking up at 6 a.m. can lead to a pattern of sleep deprivation. And that puts them at higher risk of a whole range of potential problems, from depression to automobile accidents.

So Owens says it makes sense to move school start times later. As it is now, "we are asking [teens] to be awake and alert at the time in their 24-hour clock when their alertness level is at its very lowest."

A new poll by NPR, the Robert Wood Johnson Foundation and the Harvard School of Public Health finds that 50 percent of parents of students in high school report a start time before 8 a.m. And almost 1 in 5 parents report school starting even earlier, before 7:30 a.m. (See the full results here.)

Proponents of later start times say that they're gaining traction.

"Momentum has picked up considerably in the past few years," says Terra Ziporyn Snider, executive director of Start School Later. Her group maintains a list of schools in 29 states that have made changes.

And she points to two very large school districts in the Washington, D.C., area — Fairfax County, Va., and Montgomery County, Md. — that are both considering later starts. A petition in Montgomery County started by activist Mandy Mader to push high school start times to 8:15 or later has garnered more than 11,000 signatures.

But there are logistical obstacles. Transportation is one. How do schools rearrange bus schedules to pick up high school students later, without alarming the parents of elementary school kids who might be picked up earlier to accommodate the changes?

Parents opposed to later school start times point to issues such as day-care schedules and after-school jobs. Coaches say later dismissal times would interfere with team practices.

But given the fact that many schools have already overcome these obstacles and moved to later school start times, Ziporyn Snider says, "the real problem isn't sports or jobs or day care; the real problem is fear of change and failure of imagination."

And failure to act, advocates say, is putting high school students at greater risk.

There's a gathering body of evidence to suggest that pushing back school start times can cut the risk of car crashes. In Fayette County, Ky., the number of car accidents caused by teenage drivers dropped almost 17 percent in the two years after the county pushed start times back an hour to 8:30 a.m. That compares with an 8 percent increase in crashes among 17- and 18-year-old drivers statewide over the same time.

Despite the biological and societal nudging that keeps many teenagers awake well past midnight, it does help when parents set a bedtime, experts say — even if that bedtime is 11:30 p.m.

Teens whose parents set a bedtime are more likely to get enough sleep and function better at school, a recent study found. Owens says: "If a parent sets a bedtime, it at least gets the message across that [they] feel it's important."

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

RENEE MONTAGNE, HOST:

Those with teenagers in the house have most likely experienced the conflicts between the need for sleep and the need to wake up in time for school. As part of our Education and Health poll, we inquired about school start times.

NPR's Allison Aubrey reports.

ALLISON AUBREY, BYLINE: Parents of teenagers, and I include myself in this group, face a lot of challenges that we never fully anticipated. Take for instance, the role of family timekeeper. Many of us become the morning nudger-in-chief, coaxing grumpy, surly teens out of bed before the sun comes up.

Mom Christina Sevin knows the drill. Her 15-year-old son Isaac's first alarm goes off at 6:05 a.m.

(SOUNDBITE OF AN ALARM)

AUBREY: And when he sleeps right through this alarm, Cristina starts the nudging.

(SOUNDBITE OF KNOCKING)

ISAAC SEVIN: Hey.

CHRISTINA SEVIN: Hey Isaac, are you up?

AUBREY: Cristina scrambles to get the coffee going and make a quick breakfast, and she's also tried to wake up her other teenager, 16-year-old Lilly.

SEVIN: I hear footsteps, so I think one of them is up.

AUBREY: It's Isaac.

SEVIN: It's 6:14 and really dark.

AUBREY: Inside Lilly's room, the lights are on, but she's groggy.

SEVIN: Lilly.

LILY SEVIN: Yeah?

SEVIN: You got it to get up.

AUBREY: School starts at 7:17 each morning, and they need to be out the door for the bus by 6:35.

SEVIN: I wish I didn't have to be awake right now. It's 6:22.

AUBREY: She barely has time to wash her face and brush her teeth. As she grabs a big to-go cup of black tea, she says, why, why can't school start later?

SEVIN: Yeah, I think even just an hour.

AUBREY: Lilly Sevin is not alone. Our poll found that about half of parents of high school students report a start time before 8 a.m., and almost one-in-five families report school starting even earlier, before 7:30.

And, according to Lilly, this just makes life hard.

SEVIN: I can't really function until sun goes down. I feel like with homework and all that stuff, and then that carries over till like at least 11.

AUBREY: Or midnight. Sometimes it's one or two. So like many high-schoolers, she's not getting anywhere close to the eight or nine hours of sleep she needs.

Judith Owens of Children's National Medical Center knows this problem all too well.

JUDITH OWENS: I'm not at all surprised. That's a very common scenario.

AUBREY: And there's good reason. Owens says, beginning in puberty, the biological clock starts to shift, making it harder for teens to fall asleep at what parents consider a reasonable time.

OWENS: Adolescents are basically programmed to fall asleep at about 11 p.m. or later.

AUBREY: So, waking teens for school at 6 a.m.? Owens says it makes no sense.

OWENS: We are actually asking them to be awake and alert and awake at the time in their 24 hour clock when their alertness level is at their very lowest.

AUBREY: So what to do? Well, lots of families, including Lilly and Isaac Sevin's, are getting involved in campaigns to change school start times.

One petition promotes legislation that would prevent public school from starting before 8 a.m. It has thousands of signatures from people in all 50 states.

Owens says, there would likely be multiple benefits from starting school later. Take for instance, teenage car crashes.

OWENS: Drowsy driving is a huge concern.

AUBREY: She points to a school district in Kentucky where the high school start time was changed to begin one hour later in the morning.

OWENS: And they found after the change the percentage of students involved in drowsy driving crashes went down by 16 percent.

AUBREY: Compared to previous years.

Owens says teens who sleep in a bit later might be less grumpy and more alert in school. She also points to another potential benefit. A National Sleep Foundation poll that found adolescents who got the least sleep were more likely to struggle emotionally. They reported...

OWENS: Symptoms of depression, more negative emotions, more hopelessness about the future.

AUBREY: And now, after years of debate over all the obstacles to changing school start times - from disruptions in bus schedules, to after-school care and sports practice - advocates say momentum for change is starting to build.